Nature of HLA-associated predisposition to childhood acute lymphoblastic leukemia

A molecular analysis was carried out in 63 sequentially diagnosed childhood acute lymphoblastic leukemia (ALL) patients and 1011 controls to investigate the homozygosity rate for HLA-DR53. HLA-DR53 is associated with acute myeloblastic leukemia at the protein level, and our previous study has shown its association with early-onset chronic myeloid leukemia only in homozygous form at the DNA level. In the present study, the homozygosity rates for DR53 were 17.5 and 13.6% in patients and controls, respectively. Ten of the 11 homozygous patients were boys. In the common ALL group (n = 40), all seven DR53 homozygous patients were boys, and among 19 girls this genotype was not observed (P = 0.006). For males, homozygosity for DR53 revealed a relative risk (RR) of 3.29 (P = 0.008) for common ALL. Five of the 11 relapsed patients were homozygous for DR53. Heterozygous frequencies for HLA-DR53 were not different between patients and controls. Homozygosity for DR53 was associated with a very high relapse rate (45.5 vs 7.7%, P = 0.002, RR = 9.1). These results extended our findings in chronic myeloid leukemia and showed the recessive nature and the male predominance of the interactive HLA influence on the development of childhood leukemia. Molecular mimicry of an HLA-DR53 epitope by oncogenic (retro)viruses or putative susceptibility genes in linkage disequilibrium with HLA-DR53 may be responsible for this association.     

Interaction of beta-lactam antibiotics with H+/peptide cotransporters in rat renal brush-border membranes

Two H+/peptide cotransporters, PEPT1 and PEPT2, are expressed in the kidney, mediating the renal tubular reabsorption of oligopeptides and beta-lactam antibiotics. We examined the interactions of beta-lactam antibiotics with peptide transporters in rat renal brush-border membranes by evaluating the inhibitory potencies of the antibiotics against glycylsarcosine transport. Western blot analysis revealed that PEPT1 and PEPT2 were expressed in the renal brush-border membranes with the apparent molecular masses of 75 and 105 kDa, respectively. Using renal brush-border membrane vesicles, the uphill transport of glycylsarcosine was observed in the presence of an inward H+ gradient and an inside-negative membrane potential. Two transport systems with high affinity (Km of 50 microM) and low affinity (Km of 1.2 mM) appeared kinetically to mediate the glycylsarcosine uptake. The inhibition constants of the antibiotics for glycylsarcosine transport were more closely correlated with those in stable LLC-PK1 cells transfected with rat PEPT2 rather than PEPT1 cDNA. The beta-lactam antibiotics with an alpha-amino group showed trans-stimulation effects on the glycylsarcosine uptake, suggesting that these antibiotics and glycylsarcosine share a common peptide transporter. However, the antibiotics lacking an alpha-amino group failed to show the trans-stimulation effect. It is concluded that amino-beta-lactam antibiotics at therapeutic concentrations interact predominantly with PEPT2 localized in the brush-border membranes of rat kidney.     

Computation and design of ac shunts for testing commutation equipment

Conclusions The shunt errors were measured on an ac potentiometer type R-56. The voltage terminals of the shunt were connected to the measuring terminals by means of a twisted pair. These tests led to the following conclusions:the resistance of the shunt amounts to 119.6 ohm, which differs from the calculated value only by 0.33%; the time constant of the shunt amounts toT_s=0.835·10^–2, which satisfies (9).It is possible to conclude from the measurement results that the shunt can be used for measuring short-circuit currents with an error not exceeding 0.5%.The shunt was tested for thermal stability by passing through it 30 ka for 0.3 sec. The rise of temperature in this test did not exceed 100°C, which is below the calculated value. This circumstance is due to the fact that the shunt is short and a considerable effect is produced by the dissipation of heat away from the manganin strips in the butts and massive busbars.The shunt was extensively used in the commutation equipment laboratory of the Leningrad branch of the V. I. Lenin All-Union Electrotechnical Institute in testing high-tension equipment with satisfactory results.     

Community-wide youth exercise promotion: long-term outcomes of the Minnesota Heart Health Program and the Class of 1989 Study

The Class of 1989 Study, part of the Minnesota Heart Health Program (MHHP), involved a population-wide research and demonstration project to reduce cardiovascular disease in three intervention communities in the North-Central United States (1980-1993). Beginning in sixth grade (1983), seven annual waves of measurements were taken from students in one of the MHHP intervention communities and its matched pair (baseline N = 2,376). Self-reported data were collected at each time period describing a variety of health-related behavior, including hours of exercise engaged in per week and duration and intensity of regular physical activity. Using school as the unit of analysis, physical activity levels throughout most of the follow-up period were significantly higher in the intervention community for females. Males' average values were higher in the intervention community, but were largely statistically insignificant. Results suggest multiple intervention components such as behavioral education in schools and complementary community-wide strategies can produce lasting improvement in adolescent physical activity, particularly with female students.     

直链淀粉含量对大鼠肠道发酵产物的影响

目的:研究了不同直链淀粉含量的玉米淀粉对大鼠肠道发酵产物的影响.方法:将42只Wistar成年雌鼠随机分为7组,分别饲喂直链淀粉(AS)含量为0%、26.8%、53.8%、61.6%、75.7%、78.9%、85.8%的玉米淀粉饲料.喂养3周后解剖,测定各组体重、饲料效率及淀粉消化率、小肠内容物、盲肠内容物、盲肠组织重量以及盲肠中短链脂肪酸(SCFA)等指标.结果:61.6%AS、75.7%AS、78.9%AS和85.8%AS饲料组的淀粉表观消化率明显低于0%AS和26.8%AS饲料组.与0%AS和26.8%AS相比,高直链淀粉显著地增加了小肠内容物、盲肠内容物干重,75.7%AS组的盲肠内容物干重最高.高直链淀粉组盲肠中乙酸、丙酸和总SCFA的总量显著高于0%AS和26.8%AS组,53.8%AS组丙酸产量最高,61.6%AS组有最高丁酸和总SCFA产量,而75.7%AS有最高的乙酸、乳酸和琥珀酸产量,在高直链玉米淀粉中,78.9%AS组SCFA产量最低.结论:增加玉米淀粉中直链淀粉含量能明显降低淀粉的消化性,增加大鼠肠道中未消化残渣的量和盲肠中SCFA产量,但这种效果与直链淀粉的含量并没有明显的相关性.     

基于解耦机制的小地区短期负荷预测方法

小地区短期负荷预测是电网企业精细化管理的重要手段。针对小地区短期负荷预测的特点,提出了基于解耦机制的误差分析模型和预测机制,将短期负荷预测分为负荷水平预测和标幺曲线预测两部分。小地区负荷结构单一,标幺曲线相对稳定;负荷基数较小,负荷水平的波动比较明显;标幺曲线和负荷水平受不同因素的影响,影响机理不同,分别预测有利于提高预测精度。提出了标幺曲线和平均负荷预测方法,理论分析和实践均证明,该方法能较好地把握负荷发展规律,提高了标幺曲线和平均负荷的预测精度,使总预测效果得到了改善。     

Characteristics of tapped microstrip bandpass filter in BiNbO4 ceramics

The dielectric properties of BiNbO4 (BN ceramics) sintered at low temperature with CuO and V2O5 additives were determined. BN ceramics containing 0.07 wt% V2O5 and 0.03–0.05 wt% CuO sintered at 900 °C had a dielectric constant of 44.3, temperature coefficient of resonance frequency f of 2 p.p.m. °C-1 and Qxfo value of 22 000. A multilayer type band pass filter using tapped resonators and conventional resonators was designed at 1.855 GHz and PCS (personal communication system) applications. By adopting an input/output-tapping scheme the chip filter structure becomes simpler and needs fewer layers than using the conventional input/output-coupling scheme. The green ceramic sheet the for band pass filter was manufactured by a tape casting process and a multilayer type band pass filter was fabricated with a silver electrode. The simulated characteristics, including spurious resonance of the designed filters, are compared with the measured ones. The measured frequency of both exhibited similar tendencies. Even though the centered frequency was measured to shift about 90 MHz downward, the characteristics at pass band and spurious resonance characteristics were similar to that of a simulation. © 1998 Kluwer Academic Publishers     

The suboccipital cavernous sinus

The authors studied the microsurgical anatomy of the suboccipital region, concentrating on the third segment (V3) of the vertebral artery (VA), which extends from the transverse foramen of the axis to the dural penetration of the VA, paying particular attention to its loops, branches, supporting fibrous rings, adjacent nerves, and surrounding venous structures. Ten cadaver heads (20 sides) were fixed in formalin, their blood vessels were perfused with colored silicone rubber, and they were dissected under magnification. The authors subdivided the V3 into two parts, the horizontal (V3h) and the vertical (V3v), and studied the anatomical structures topographically, from the superficial to the deep tissues. In two additional specimens, serial histological sections were acquired through the V3 and its encircling elements to elucidate their cross-sectional anatomy. Measurements of surgically and clinically important features were obtained with the aid of an operating microscope. This study reveals an astonishing anatomical resemblance between the suboccipital complex and the cavernous sinus, as follows: venous cushioning; anatomical properties of the V3 and those of the petrous-cavernous internal carotid artery (ICA), namely their loops, branches, supporting fibrous rings, and periarterial autonomic neural plexus; adjacent nerves; and skull base locations. Likewise, a review of the literature showed a related embryological development and functional and pathological features, as well as similar transitional patterns in the arterial walls of the V3 and the petrous-cavernous ICA. Hence, due to its similarity to the cavernous sinus, this suboccipital complex is here named the "suboccipital cavernous sinus." Its role in physiological and pathological conditions as they pertain to various clinical and surgical implications is also discussed.     

A combined microsurgical skull-base and endovascular approach to giant and large paraclinoid aneurysms

BACKGROUND: The treatment of giant and large paraclinoid aneurysms remains challenging. To improve exposure, facilitate the dissection of aneurysms, assure vascular control, reduce brain retraction and temporary occlusion time, enable simultaneous treatment of associated lesions, and achieve more successful treatment of "difficult" (atherosclerotic and calcified) aneurysms, we combined the skull-base approach with endovascular balloon occlusion of the internal carotid artery (ICA) and suction decompression of the aneurysm. METHODS: Sixteen female patients were treated, eight with giant aneurysms and eight with large aneurysms. Eight aneurysms occurred on the right side and eight on the left. Eight patients had an additional aneurysm; five were clipped during the same procedure. Three patients had infundibular arterial dilation. One patient had an associated hemangioma of the ipsilateral cavernous sinus. The cranio-orbital-zygomatic approach was used for all patients. The anterior clinoid was drilled, and the optic nerve was decompressed, dissected, and mobilized. Transfemoral temporary balloon occlusion of the ICA in the neck was followed by placement of a temporary clip proximal to the posterior communicating artery. Suction decompression was then applied. All aneurysms were then successfully clipped, except one that had a calcified neck and wall that could not be collapsed. Intraoperative angiography performed in 13 of 15 patients with clipped aneurysms confirmed obliteration of the aneurysm and patency of the blood vessels. RESULTS: Postoperative results were good in 14 patients. One patient had right-sided hemiplegia and expressive aphasia, which improved after rehabilitation. One patient with an additional basilar tip aneurysm clipped simultaneously died on the fifth postoperative day because of intraventricular hemorrhage. The origin of bleeding could not be determined on autopsy. Surgical difficulties and morbidity stemmed mainly from a severely calcified or atherosclerotic aneurysmal neck. CONCLUSION: The combination of skull-base approaches and endovascular balloon occlusion coupled with suction decompression is a successful option for the treatment of these challenging aneurysms.     

Imaging electromigration during the formation of break junctions

Using a scanning electron microscope, we make real-time movies of gold nanowires during the process of electromigration. We confirm the importance of using a small series resistance when employing electromigration to make controlled nanometer-scale gaps suitable for molecular-electronics studies. We are also able to estimate the effective temperature experienced by molecular adsorbates on the nanowire during the electromigration process.